Printhead IC with actuator movement parallel to ink inlet flow

Abstract

An inkjet printhead IC is fabricated using a wafer substrate that defines a plurality of ink inlet channels. A plurality of nozzle structures fabricated on the substrate to define nozzle chambers are in fluid communication with the ink inlet channels and an ink ejection nozzle in fluid communication with each nozzle chamber. Each nozzle structure has a chamber, an ejection nozzle in fluid communication with the chamber, and an ejection member for acting on ink within the chamber. A plurality of actuators attached to the substrate move each of the ejection members respectively, the movement being substantially parallel to the ink inlet flow direction; such that, ink is ejected through the ejection nozzle upon activation of the actuator corresponding to that nozzle structure.

1. An inkjet printhead integrated circuit (IC) for a printer, the printhead IC comprising:
 a wafer substrate defining a plurality of ink inlets; 
 a plurality of nozzle structures formed on the substrate for communication with each of the ink inlets respectively, each nozzle structure having a chamber, an ejection nozzle in fluid communication with the chamber, and an ejection member for acting on ink within the chamber; 
 a plurality of actuators attached to the substrate for moving each of the ejection members respectively, the movement being substantially parallel to the ink inlet flow direction; such that, 
 ink is ejected through the ejection nozzle upon activation of the actuator corresponding to that nozzle structure. 
 
   
   
     2. An inkjet printhead IC according to  claim 1 , further comprising transistor circuitry associated with each for the actuators for receiving print data and activating the actuators accordingly, the transistor circuitry defining a plurality of transistors that are interposed between the substrate and corresponding actuators so that each actuator receives an electrical signal from one corresponding transistor. 
   
   
     3. An inkjet printhead IC according to  claim 2  in which each transistor comprises a poly layer having a plurality of the traces. 
   
   
     4. An inkjet printhead IC according to  claim 1 , in which each elongate actuator includes an actuator arm of a laminated structure comprising a resiliently flexible inner layer, a conductive layer and a compensation layer, the inner layer being interposed between the conductive and compensation layers, the conductive layer being positioned between the inner layer and the substrate and defining an electrical heating circuit such that, when heated by an electrical current received from the associated transistor, the conductive layer expands and causes the actuator arm to bend away from the substrate, with subsequent cooling and contraction resulting in the actuator arm bending back towards the substrate. 
   
   
     5. An inkjet printhead IC according to  claim 4 , in which the conductive layer defines a series of corrugations which are generally aligned with the traces. 
   
   
     6. An inkjet printhead IC according to  claim 4 , in which each ink ejection member is a paddle that is connected to the conductive layer of the respective actuator, the conductive layer defining a discontinuity between the paddle and the heating circuit to insulate the paddle from the heating circuit. 
   
   
     7. An inkjet printhead IC according to  claim 4 , in which the conductive layer and the compensation layer are of substantially the same material to compensate for stresses that are generated in the actuator arm as a result of reciprocal bending of the actuator arm.